This reverts commit 37001778.

This reverts commit 8dab6d81.

(sorry)

It now detects if different replicas have different bias-factor

[makedoc]

gaussian with grids, the check for sigma_min and
grid was not working properly

the gaussian support was wrong

- METAD: exit with error if used
- PBMETAD: gives a warning and deactivate the interval for the specific variable
close #181

I cleaned up some of the (innocuous) warnings

Same as #171 but using C++ standard include file <ctime>

Closes #171

This bug was introduced by me in 5e3aaf3a
The barrier on multi replicas was due to overcaution and
is only necessary when using WALKERS_MPI

It seems that sometime on travis a regtest with mw-mpi crashes.

I think this is because when using multiple processors per walker
there is a problem in the opening of the old file (for read) and
its backup (for write). Adding this barrier seems to make it more robust

Related to: e1b845b4

Now the type is defined with a typedef so that it is easier to change it.

I also set the type to size_t instead of unsigned long long.
This should be more portable.

Only add to the manual RESTART UPDATE_FROM and UPDATE_UNTIL
in the actions for which this makes sense